Paper-feeding device with automatic paper detecting function

ABSTRACT

A paper-feeding device includes a paper tray for holding paper, a paper advance module for picking up the paper held on the paper tray and outputting the paper, a sensing module for sensing the deformation of the paper during the feeding process and outputting a sensing signal when the paper advances in a sensing area, and a control unit for determining the paper feeding status according to the sensing signal generated from the sensing module.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a paper-feeding device, and more particularly, to a paper-feeding device for detecting paper status automatically.

2. Description of the Prior Art

Business machines are often used in offices to help with the processing of documents. These business machines include copiers, fax machines, printers, etc. To facilitate continuous document processing, these business machines all have paper feeding systems to supply paper. Since most types of business machines can only process a single-paged document a page at a time, the paper feeding system of the machine must be able to send exactly one sheet of paper each time to the machine. If the paper feeding system sends out more than one sheet of paper at a time, the sheets are likely to jam in the machine, causing delays in the entire document handling process, as well as wasting paper. Therefore, it is of great importance that a paper feeding system that can feed exactly one sheet of paper at a time be designed.

In general, there are two types of feeding motors of paper feeding systems. One is a DC motor module, and the other is a stepping motor module. The paper feeding system with the DC motor module includes a DC motor, an encoder, and a stripe. The encoder and the strip can feed back velocity and location of paper for dealing with paper immediately during the situation that a feeding roller is driven by the DC motor and paper does not slide on the feeding roller. But in this way there are more necessary components and the cost will increase. In addition, the control method is more complicated.

Furthermore the paper feeding system with the stepping motor module only provides a feeding sensor and a stepping motor for feeding paper instead of detecting paper status. Because the immediate status of paper cannot be detected, such as a paper jam, the system cannot deal with paper immediately.

In addition, for upgrading the printer quality, noise control is one of the important things. Nowadays the noise generated during operation is mostly caused by motors, especially in the event of a breakdown of the stepping motor. Therefore if the breakdown of the steeping motor cannot be repaired immediately, the noise problem cannot be solved.

SUMMARY OF INVENTION

It is therefore a primary objective of the claimed invention to provide a paper-feeding device for detecting paper status automatically to solve the above-mentioned problems.

According to the claimed invention, a paper-feeding device includes a paper tray for holding paper, a paper advance module for picking up the paper held on the paper tray and outputting the paper, a sensing module for sensing the deformation of the paper during the feeding process and outputting a sensing signal when the paper advances in a sensing area, and a control unit for determining the paper feeding status according to the sensing signal generated from the sensing module.

According to the claimed invention, a paper-feeding method includes feeding a paper, outputting a sensing signal according to deformation of the paper during the feeding process, and determining whether the paper advances normally or not according to the sensing signal.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram of a printer according to the present invention.

FIG. 2 is a schematic diagram of the printer feeding paper.

FIG. 3 is a functional block diagram of the printer.

FIG. 4 is a flowchart of paper-feeding mechanism according to the present invention.

FIG. 5 is a schematic diagram of the paper deforming in the sensing area.

FIG. 6 is a signal oscillogram of a motor and a sensing module when the paper advances normally.

FIG. 7 is a signal oscillogram of the motor and the sensing module when the paper jams.

FIG. 8 is a schematic diagram of a sensing module detecting deformation of the paper of another embodiment according to the present invention.

DETAILED DESCRIPTION

Please refer to FIG. 1 and FIG. 2. FIG. 1 is a diagram of a printer 10 according to the present invention. FIG. 2 is a schematic diagram of the printer 10 feeding paper. The printer 10 includes a paper tray 12 for holding paper 14, a paper holder 16 for holding the paper 14, a carriage 18 for moving on a shaft 20, an ink box 22 installed on the carriage 18 for providing ink to print the paper 14. The printer further includes a paper advance module 24. The paper advance module 24 includes a pickup roller 26 installed above the paper tray 12 in a rotatable manner for picking up the paper 14 held on the paper tray 12, a feed roller 28 installed in front of the bottom of the paper tray 12 in a rotatable manner for driving the paper 14 to move along an advancing direction, and a motor 30 for driving the pickup roller 26 and the feed roller 28. The motor 28 can be a stepping motor or a DC motor. The printer 10 further includes a sensing module 32 for sensing a deformation of the paper 14 during the feeding process and outputting a sensing signal, and a paper constrainer 34 for constraining the buckling deformation of the paper 14 when the paper 14 enters sensing area of the sensing module 32.

Please refer to FIG. 3. FIG. 3 is a functional block diagram of the printer 10. The printer 10 further includes a control unit 36 electrically connected to the sensing module 32 and the motor 30 for determining the feeding status of the paper 14 according to the sensing signal outputted from the sensing module 32 and controlling the motor 30 according to the feeding status of the paper 14. The control unit 36 includes an amplifier 38 for amplifying the buckling deformation of the paper 14 detected by the sensing module 32, and an analog-to-digital converter 40 for converting analog signals outputted from the amplifier 38 into digital signals. The printer 10 further includes a display unit 42 electrically connected to the control unit 36 for presenting the status of the paper 14 detected by the sensing module 32.

Please refer to FIG. 4. FIG. 4 is a flowchart of paper-feeding mechanism according to the present invention. The method includes the following steps:

Step 100: The paper advance module 24 starts feeding the paper 14.

Step 102: The sensing module 32 detects the buckling deformation of the paper 14 and outputs a corresponding sensing signal to the control unit 36.

Step 104: The control unit 36 determines the feeding status of the paper 14 such as whether the paper 14 advances normally according to the corresponding sensing signal. If the paper 14 advances normally, the paper 14 continues advancing until the paper 14 advances out completely. And if the paper 14 advances abnormally, go to Step 106.

Step 106: The control unit 36 generates an interrupt signal to the motor 30. When the motor 30 receives the interrupt signal from the control unit 36, the motor 30 stops the paper advance module 24 from feeding the paper 14.

Step 108: Finish feeding the paper 14.

The detailed description of the above-mentioned steps is introduced as follows. The motor 30 generates the feeding power of the paper advance module 24 of the printer 10. The motor 30 drives the pickup roller 26 and the feed roller 28 to rotate, and the paper 14 advances by the static frictional force between the paper 14 and the surface of rollers after the pickup roller 26 and the feed roller 28 feed the paper 14. Please refer to FIG. 5. FIG. 5 is a schematic diagram of the paper 14 deforming in the sensing area. After the paper 14 advances into the feed roller 28, the motor 30 drives the feed roller 28 to feed the paper 14 so that the front end of the paper 14 advances by the frictional force between the paper 14 and the surface of the feed roller 28. Due to the sudden advance of the paper 14, the front of the paper 12 will experience a buckling deformation. And because the range of the buckling deformation is located above the sensing module 32, the sensing module 32 can measure the deforming variation of the paper 14. The sensing module 32 can be a reflective-type sensor for emitting a sensing signal to the paper 14 and receiving the sensing signal reflected from the paper 14 to calculate the deformation of the paper 14. The sensing module 32 can include only one sensor or a plurality of sensors, and the sensor can be a breaking-type sensor, a reflective-type sensor, a receiving-type sensor, and so on. After the paper 14 advances into the sensing area, the deformation magnitude of the paper 14 has to be limited so that the deformation of the paper 14 can be located within the measurable range of the sensing module 32. Therefore, the paper constrainer 34 can constrain the buckling deformation of the paper 14 when the paper 14 advances into the sensing area of the sensing module 32. The distance between the paper constrainer 34 and the sensing module 32 can be 5 mm, that is, the deformation of the paper 14 is limited within 5 mm. The distance between the paper constrainer 34 and the sensing module 32 can be designed according to the measurable range of the sensing module 32.

When the paper 14 starts advancing, the paper holder 16 does not apply any force on the paper 14 so that the end nearby the paper holder 16 of the paper 14 is a free end and the paper can be deformed in a wave motion. After the paper 14 finishes advancing, the paper holder 16 can hold the paper 14 that has not been fed yet. During the feeding procedure the end nearby the pickup roller 26 of the paper 14 is not fixed by the paper holder 26 so as to be a free end, and the end nearby the feed roller 28 of the paper 14 can be regarded as a fixed end for fixing the paper 14 so that the paper 14 can advance with the feed roller 28 simultaneously instead of sliding. In addition, because one end of the paper 14 is a free end and the other end of the paper 14 is a fixed end, the paper 14 can experience a buckling deformation easily for providing the basis of generating sensing signals by the sensing module 32.

Please refer to FIG. 6. FIG. 6 is a signal oscillogram of the motor 30 and the sensing module 32 when the paper 14 advances normally. When the paper 14 advances normally and every time the motor 30 receives a driving signal, the paper 14 can advance at a small distance along the advancing direction. Due to the sudden advance of the paper 14, the front of the paper 12 will experience a buckling deformation. Therefore the sensing module 32 detects the deformation variation of the paper 14 and generates a corresponding response signal. The time interval between the driving signal of the motor 30 and the response signal generated by the sensing module 32 is small because after generating the driving signal of the motor 30, the sensing module 32 detects the deformation variation of the paper 14 and generates the response signal timely. The above-mentioned situation is the normal situation of feeding procedure. Please refer to FIG. 7. FIG. 7 is a signal oscillogram of the motor 30 and the sensing module 32 when the paper 14 jams. When the paper 14 jams, even if the motor 30 continues receiving the driving signal and the motor 30 rotates, the paper 14 cannot advance normally. Therefore there is no buckling deformation of the paper 14 due to the sudden advance of the paper 14. And the sensing module 32 cannot detect the deformation variation of the paper 14 and cannot generate the corresponding response signal. The buckling deformation of the paper 14 detected by the sensing module 32 can be transmitted to the control unit 36. The amplifier 38 can amplify the signal, and then the analog-to-digital converter 40 can convert the analog signal outputted from the amplifier 38 into the digital signal. The control unit 36 can determine whether the paper 14 advances normally or not according to the digital signal generated by the analog-to-digital converter 40 and the above-mentioned criteria.

When the paper 14 advances normally, the paper 14 continues advancing until the paper 14 advances out completely. When the paper 14 jams, the control unit 36 can generate an interrupt signal to the motor 30. After the motor 30 receives the interrupt signal from the control unit 36, the motor 30 stops the paper advance module 24 from feeding the paper 14. That is, the feeding procedure is over. The control unit 36 also can transmit a signal to the display unit 42 for displaying the paper jam status. The display method can use either light or sound for warning users about the abnormal feeding status. Because the control unit 36 can adjust the operation of the motor 30 timely according to the sensing signal generated from the sensing module 32, the print efficiency can be increased and the noise due to the motor 30 out of control can be reduced. That is, the control unit 36 can determine feeding status of the paper 14 according to the sensing signal generated from the sensing module 32 and generate a feedback signal to control the print procedure and the operation of the motor 30. It is a closed-loop feedback control method for controlling the print procedure and the feeding status of the paper 14.

The sensing module 32 can detect the deformation of the paper 14 by using a strain gauge. Please refer to FIG. 8. FIG. 8 is a schematic diagram of a sensing module 44 detecting deformation of the paper 14 of another embodiment according to the present invention. The sensing module 44 includes a transmission link 46 having one end to contact the paper 14, a spring 48 sheathed on the transmission link 46, and a deformation sensor 50 installed on the spring 48 for sensing deformation of the spring 48 tugged by the deformation of the paper 14 during the feeding process. The deformation sensor 50 can be a strain gauge, a tensiometer, a contact probe, a sensor made of piezoelectric material, and so on. For example, if the deformation sensor 50 is a strain gauge, the strain gauge will generate different voltage magnitudes according to different deformations of the paper 14 due to that one end of the transmission link 46 contacts the surface of the paper 14 slightly for transferring the motion status of the paper 14 to the strain gauge via the spring 48. The voltage value generated by the strain gauge can be outputted to a converting circuit 52 for converting the voltage value into the corresponding deformation of the paper 14 and transmitting the deformation data to the control unit 36 so as to determine the feeding status of the paper 14. Furthermore, the control unit 36 can generate a feedback signal to control the print procedure and the operation of the motor 30.

In contrast to the prior art, the present invention provides a paper-feeding device that can detect deformation of the paper 14 during the feeding procedure with the sensing module 14 and generate the corresponding sensing signal to the control unit 36 for adjusting the operation of the motor 30 timely according to the corresponding sensing signal transmitted from the sensing module 32. Therefore the print efficiency can be increased and the noise due to the motor 30 out of control can be reduced. That is, the control unit 36 can determine feeding status of the paper 14 according to the sensing signal generated from the sensing module 32 and generate a feedback signal to control the print procedure and the operation of the motor 30. The present invention uses a closed-loop feedback control method for controlling the print procedure and the feeding status of the paper 14. The paper-feeding device according to the present invention can be used for printers, faxes, multi-function products (MFP), and so on. The present invention can detect status of the paper 14 and adjust the operation of the paper advance module 24 so that the paper jam problem can be solved immediately to avoid noise, and the efficiency and value of products can be upgraded.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and the method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims. 

1. A paper-feeding device comprising: a paper tray for holding paper; a paper advance module for picking up the paper held on the paper tray and outputting the paper; a sensing module for sensing the deformation of the paper during the feeding process and outputting a sensing signal when the paper advances in a sensing area; and a control unit for determining the paper feeding status according to the sensing signal generated from the sensing module.
 2. The paper-feeding device of claim 1 wherein the paper advance module further comprises: a pickup roller installed above the paper tray in a rotatable manner for picking up the paper held on the paper tray; a feed roller installed in front of the bottom of the paper tray in a rotatable manner for driving the paper to move in an advancing direction; and a motor for driving the pickup roller and the feed roller.
 3. The paper-feeding device of claim 1 further comprising a paper holder for holding the paper before the paper advances in the sensing area.
 4. The paper-feeding device of claim 1 wherein the motor is a stepping motor.
 5. The paper-feeding device of claim 1 wherein the motor is a DC motor.
 6. The paper-feeding device of claim 1 wherein the sensing module outputs a sensing signal according to a buckling deformation of the paper during the feeding process.
 7. The paper-feeding device of claim 6 further comprising a paper constrainer for constraining the buckling deformation of the paper during the feeding process.
 8. The paper-feeding device of claim 7 wherein the distance between the paper constrainer and the sensing module is less than 5 mm.
 9. The paper-feeding device of claim 6 wherein the sensing module is a reflective-type sensor for emitting a sensing signal to the paper and receiving the sensing signal reflected from the paper to calculate the deformation of the paper.
 10. The paper-feeding device of claim 6 wherein the control unit comprises an amplifier for amplifying the buckling deformation of the paper detected by the sensing module, and an analog-to-digital converter for converting analog signals outputted from the amplifier into digital signals.
 11. The paper-feeding device of claim 1 wherein the sensing module comprises: a transmission link with one end used to contact the paper; a spring sheathed on the transmission link; and a deformation sensor installed on the spring for sensing deformation of the spring tugged by the deformation of the paper during the feeding process.
 12. The paper-feeding device of claim 11 wherein the deformation sensor is a strain gauge.
 13. The paper-feeding device of claim 11 wherein the deformation sensor is a sensor made of piezoelectric material.
 14. The paper-feeding device of claim 1 wherein the control unit can output a feedback signal to the paper advance module for modifying action of the paper advance module according the sensing signal outputted by the sensing module.
 15. The paper-feeding device of claim 14 wherein when the paper advance module receives the feedback signal transmitted from the control unit, the paper advance module stops the feeding process.
 16. A paper-feeding method comprising: feeding a paper; outputting a sensing signal according to deformation of the paper during the feeding process; and determining whether the paper advances normally or not according to the sensing signal.
 17. The method of claim 16 further comprising if the paper advances normally, continuing feeding the paper until the paper slides out completely, and if the paper advances abnormally, stopping the feeding process.
 18. The method of claim 16 wherein the deformation of the paper during the feeding process is a buckling deformation. 